The semiconductor integrated circuit (IC) industry has experienced rapid growth. Continuing advances in semiconductor manufacturing processes have resulted in semiconductor devices with finer features and/or higher degrees of integration. Functional density (i.e., the number of interconnected devices per chip area) has generally increased while feature size has decreased. This scaling-down process generally provides benefits by increasing production efficiency and lowering associated costs.
Despite groundbreaking advances in materials and fabrication, scaling planar devices such as a metal-oxide-semiconductor field effect transistor (MOSFET) device has proven challenging. To overcome these challenges, circuit designers look to novel structures to deliver improved performance, which has resulted in the development of three-dimensional designs, such as fin-like field effect transistors (FinFETs). The FinFET is fabricated with a thin vertical “fin” (or fin structure) extending up from a substrate. The channel of the FinFET is formed in this vertical fin. A gate is provided over the fin to allow the gate to control the channel from multiple sides. Advantages of the FinFET may include a reduction of the short-channel effect, reduced leakage, and higher current flow.
However, since feature sizes continue to decrease, fabrication processes continue to become more difficult to perform. Therefore, it is a challenge to form a reliable semiconductor device including the FinFET.